Weight-loss surgery after age 35 linked to survival benefit

(Reuters Health) - Obese people who undergo a certain kind of weight-loss operation after age 35 may live longer than obese people of the same age who don't have the surgery, a study suggests.

The findings, reported in JAMA Surgery, show that the so-called gastric bypass operation is associated with a mortality benefit along with its better-known "metabolic" benefits, said lead author Lance Davidson, of Brigham Young University in Provo, Utah.

He told Reuters Health the benefit is "pretty significant and pretty convincing."

In a gastric bypass procedure - formally known as Roux-en-Y gastric bypass - surgeons reduce the size of the stomach and also reconstruct the gastrointestinal tract so that food will bypass part of the intestines as it's being digested.

Past research has found weight loss surgeries are tied to reduced deaths from any cause, cancer and heart disease. Those studies left several unanswered questions, however.

Specifically, why are deaths from so-called external causes - like accidents and poisoning - more common among people who have weight loss surgery? Also, does the reduced risk of death apply to older people undergoing weight loss surgeries?

For the new study, the researchers studied 7,925 patients who had gastric bypass between 1984 and 2002, and 7,925 similarly obese patients who didn't have surgery.

Over the next seven years, surgery patients ages 35 through 44 were 46 percent less likely to die from any cause than people who didn't undergo surgery.

Similarly, people ages 45 through 54 had a 57 percent reduced risk of death and people age 55 through 74 years had about a 50 percent reduced risk of death.

There was no difference in death rates among people under age 35, however. The researchers found the lack of difference is primarily due to the increased risk of death from external causes being concentrated among women in that age group.

For women under age 35, the risk of dying from an external cause was over three times greater for those who had gastric bypass than those who didn't have surgery.

Davidson said the new study can't say why young women who have gastric bypass surgery are at an increased risk of death from external causes.

It could be, he added, that we would see a reduced risk of death in these younger patients, too, if researchers followed them for another decade or so.

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Weight-loss surgery after age 35 linked to survival benefit

John Goodman - 1991

Cheerful John Goodman in a scene from the film 'Barton Fink', 1991. (Photo by 20th Century-Fox/Getty Images)

John Goodman - 2015

John Goodman attends the 'Trumbo' Accenture Gala during the BFI London Film Festival at Odeon Leicester Square on October 8, 2015 in London, England. (Photo by Mark Cuthbert/UK Press via Getty Images)

Khloe Kardashian - 2007

Khloe Kardashian at the 'Keeping Up With The Kardashians' premiere party on October 9, 2007 in West Hollywood, California. (Photo by Jeff Vespa/WireImage)

Khloe Kardashian - 2015

Khloe Kardashian appears At ULTA Beauty's West Hills Store To Promote Kardashian Beauty Hair Care And Styling Line at ULTA Beauty on April 2, 2015 in West Hills, California. (Photo by Frazer Harrison/Getty Images)

Kelly Osbourne, daughter of rocker Ozzy Osbourne at St Martin's Lane Hotel, London, August 21, 2002. Kelly, along with brother Jack, mother Sharon and father Ozzy, are the stars of their own reality television show, 'The Osbournes'. (Photo by Gareth Davies/Getty Images)

Kelly Osbourne - 2015

Special guest Kelly Osbourne celebrates the opening of the new Cost Plus World Market Chelsea, New York store on August 18, 2015 in New York City. (Photo by Jamie McCarthy/Getty Images for World Market)

Chaz Bono - 2010

Chaz Bono arrives at the 21st Annual GLAAD Media Awards held at Hyatt Regency Century Plaza on April 17, 2010 in Century City, California. (Photo by Angela Weiss/Getty Images)

As for older obese people considering gastric bypass, Davidson said the benefits are likely larger as people get older because deadly conditions related to obesity are more likely to occur as people age.

"I'd say if they qualify for it and are safe to undergo that surgery, the mortality and metabolic benefits are pretty strong," he said.

But the new results should be interpreted with caution, said Dr. Malcolm Robinson, of Harvard Medical School and Brigham and Women's Hospital in Boston, wrote in an accompanying editorial.

"Bariatric surgeons exclude high-risk patients from surgery, which represents the major flaw in this study," wrote Robinson. In other words, the obese people who had the surgery were a relatively healthy group to start with.

Davidson said bariatric surgery patients tend to be the most obese, however.